Vacuum relay



United States Patent O 3,541,484 VACUUM RELAY Victor E. De Lucia, LosAngeles, Calif., assignor to Torr Laboratories, Inc., Los Angeles,Calif., a corporation of California Filed Dec. 23, 1968, Ser. No..786,211 l Int. Cl. H01h 1/18 U.S. Cl. 335--196 8 Claims ABSTRACT F THEDISCLOSURE An improved construction for a miniature vacuum relay isprovided. The relay includes an evacuated envelope in which the movableand iixed contacts of the relay are housed. The movable Contact issupported on a magnetic armature within the envelope, in position tomake and break selectively with the fixed contacts of the relay. Afeature of the relay of the invention is the establishment of aconnection from an external terminal to the movable contact by means ofa U-shaped resilient spring whose side members extend along both sidesof the path of the movable contact, and Whose side members are biasedagainst the movable contact in electrical contact therewith. The designof the relay is such that there is no tendency for the relay to bind orto get into a hung up condition.

BACKGROUND OF THE INVENTION The vacuum relay to be described includes amovable armature and magnetic pole pieces enclosed in an evacuated glassor ceramic envelope. The energizing coil for the relay, and the majorpart of its magnetic circuit, are mounted externally of the envelope.This construction is advantageous in that the relay responds with highsensitivity to the energizing of its coil, since the magnetic circuitprojects directly into the evacuated envelope. The ceramic envelope maybe used for high frequency applications, and glass seals are provided toobviate leakage which is often encountered in the prior art ceramicrelays.

The vacuum relay of the invention is of the general type which comprisesan evacuated chamber formed by the aforesaid glass or ceramic envelope,and which is closed at one end by a metallic end Wall. The magnetizablecore of the relay extends through the metallic end wall, and it is usedto draw a pivotally mounted magnetic armature in towards the end of thecore. The armature is pivotally mounted within the chamber on the innerface of the end wall, and it is normally spring biased away from the endwall.

In the construction of the present invention, an insulating postcomposed, for example, of sapphire, is staked to the armature, a highlyconductive metallic sleeve is fitted over the post, and the movablecontact of the relay is formed by a conductive collar which is supportedon an under cut end portion of the conductive sleeve at the outer end ofthe post. The fixed contacts are in the form of conductive pins whichextend through the glass envelope of the relay and into the evacuatedchamber. These pins are configured so that their ends extend across thepath of the movable contact, in front of and behind the movable contact,so as to be selectively contacted thereby as the armature is movedbetween its two pivotal positions. Both the movable contact and thelixed contacts are preferably formed of a refractory material, such astungsten or molybdenum for long operational life. The refractory movablecontact is backed up by the highly conductive sleeve. The sleeve andmovable contact, as Well as the insulating post are all assembled to thearmature mechanically and no brazing, welding or soldering is required,so that there is no oxidizing of the components during fabrication.

A connection is made to the movable contact from a third electricallyconductive common pin extending through the glass or ceramic envelope.This latter connection has the form of a U-shaped resilient spring, andthe movable contact slides between the side members of the spring as thearmature moves from one pivotal position to the other. The side membersof the spring are resiliently biased against the sides of the aforesaidconductive sleeve so as to maintain a continuous electrical contact withit. The sleeve and U-shaped spring serve to complete the electricalcircuit between the movable contact and the common conductive pin.

The construction of the improved miniature vacuum relay of the presentinvention is advantageous in that no twisting or turning motions of themovable contact assembly are developed in the relay. This is because, asthe armature moves from one of its pivotal positions to the other, themovable contact and associated components move with the armature,without any twisting or turning movement, as is the case with most ofthe prior art relays of the same general type. This obviates anytendency for the relay to bind or to get hung up. Also, thisconstruction enables the relay to exhibit extremely long operationallifetime characteristics. Moreover, the relay of the invention is easyto construct in that the fixed contacts and the U-shaped spring may bemounted in the envelope as a lirst sub-assembly, and the othercomponents may be mounted on the base as a second sub-assembly, with thetwo sub-assemblies being subsequently joined together by a simpleheliarc operation.

The miniature relay to be described is particularly suited for highvoltage applications, and it does not exhibit any tendency todeteriorate when used with high voltages and peak currents, even underhigh ambient temperature conditions. Also, and as described above, thesimple movement of the movable contact assembly and armature of therelay obviates any tendency for it to stick or otherwise malfunctionduring its operation.

iBRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side section of a relayconstructed in accordance with the concepts of the present invention;

FIG. 2 is a cross sectional view taken along the line 2-2 of FIG. l; andY FIG. 3 is a sectional view of the armature sub-assembly of the relay.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT As illustrated in thedrawing, the miniature vacuum relay of the present invention comprisesan evacuated envelope 10. The envelope may be formed of glass, ceramicor any other appropriate material. The envelope is closed at its lowerend by a metallic non-magnetic ring 11 which, together with the envelope10, and the magnetic structure to be described, define an evacuatedchamber in which the operating components of the relay are situated.

A magnetizable core 12 extends through the ring 11, as shown. A magnetichousing 13 surrounds the core, and it has an annular end portion 13a.The end portion 13a, together with the core 12 and ring 11 constitutethe end wall for the evacuated chamber. An armature 14 is pivotallymounted within the evaucated chamber on the end portion 13a, formovement towards and away from the inner end of the core 12. An electriccoil 16 is mounted externally of the envelope within the housing 13, andit surrounds the core 12. A spring 18 normally biases Nthe armature 114to the tilted condition shown in FIG. 1.

However, when the coil 16 is energized, the resulting magnetismestablished in the core 12 draws the armature in against the end of thecore against the biasing action `of the spring 16. The end portion 13ais attached to the envelope 10 by means of a ring 19. The ring 19 may beformed of Kovar or other appropriate material. When the envelope isformed of ceramic, a glass frit seal may be used between the ring 19 andthe envelope 10` to obviate any tendency to leakage.

An insulating post 20 formed, for example, of sapphire, is staked to thearmature 14, and the post extends outwardly from the plane of thearmature. The post 20 is surrounded by an electrically conductive sleeve22 (FIG. 3). This sleeve, for example, may be formed of berylliumcopper, or other high conductivity material, and it may be silverplated. The post may be ground to a velvet iinish to provide frictionalresistance suicient to hold the sleeve in a press fit relationshiptherewith.

'I'he movable contact of the relay is in the form of a collar 24 which,as shown in FIG. 3, is tted over the end of the sleeve 20 which mayappropriately be under cut to have a reduced outer diameter, as shown.The end of the sleeve 22 is rolled over to hold the collar 24 in place.The collar 2.4 is in electrically conductive relationship withthe sleeve22, so that the sleeve provides a good high conductive backing for thecollar 24. The collar is formed, for example, of an electricallyconductive material having high refractory characteristics, such asmolybdenum or tungsten, so as to be capable of breaking relatively highcurrents without deterioration. The movable contact 24 may, if sodesired, be formed of a tungsten-rhenium alloy, or atungsten-rhenium-osmium alloy (70%-20%51%). A feature of thearmature-movable contact assembly 14, 20, 22 and 24 is that it requiresno brazing, soldering or Welding for its construction which would tendto oxidize and contaminate the various components. The sleeve 22, asnoted, may be composed of high conductive material, such as berylliumcopper, and it may be silver plated to provide lubricated slidingcontactvcharacteristics for continuous sliding contact with a springcomponent to be described. A. The fixed contacts of the relay areformed, for example, by a pair of electrically conductive pins 30 and 32formed of tungsten or other electrically conductive material of highrefractory characteristics. The pins 30= and 32 extend through theenvelope 10 into the interior, and the lower ends of the pins are bentover to extend across the path of the movable contact collar 24 in frontof and behind the movable contact respectively. The pins 30 and 32 arepositioned so that the pin 30, for example, is engaged by the movablecontact collar 24 when the armature 14 is in its tilted position shownin FIG. l, and so that the pin 30 will be engaged by the movable contactcollar 24 when the relay is energized to draw the armature 14 againstthe end of the core 12.

Connection is established to the movable contact collar 24 hy means of athird electrically conductive pin 36 which extends through the top ofthe envelope 10. A U-shaped spring 38 is axed to the lower end of thepin 36 by spot welding or the like. The spring 38 has a pair of sidemembers which extend parallel to the path of the armature assembly onboth sides of the sleeve 22, s0 that the sleeve slides along the innersurfaces of the spring 38. The spring 38 may be formed, for example, ofheattreated beryllium copper, and its side members are spring biasedinwardly towards one another and against the sleeve 22. The spring 38also may be silver plated to provide a lubricated continuous slidingcontact with the sleeve 22.

The spring biasing tension of the spring is made sufcient so that apositive contact is maintained thereby between the pin 36 and the sleeve22 even after long operating intervals have produced wear to theaifected parts. The sleeve 22 is in electrically conductive relationshipwith the movable contact 24, so that electrical connection isestablished from the pin 36 through the spring 38 and through the sleeve22 to the movable contact 24. Moreover, a positive and continuouscontact is maintained without any tendency for interruption, as themovable contact moves back and forth along its path.

For high frequency uses, and as described above, a ceramic envelope maybe used. As also described, when such an envelope is used, glass sealsare incorporated, so that the desired electrical characteristics of theceramic may be utilized in conjunction with the ease and reliability ofglass in forming and maintaining vacuum tight integrity in the assembly.

The invention provides, therefore, an improved vacuum relay which isconstructed so that it may operate satisfactorily over long periods oftime, even in conjunction with extremely high voltages and peakcurrents, and even under high temperature ambient conditions.

What is claimed is:

1. In a vacuum relay which includes an envelope, a magnetic membermounted on an endv Wall of said envelope and extending into the interiorof said envelope, an armature positioned in said envelope pivotallymounted on said end wall, a rst electrically conductive pin extendingthrough the envelope into the interior thereof, and a secondelectrically conductive pin extending through the envelope into theinterior thereof, the combination of: a U-shaped resilient electricallyconductive spring mounted in said envelope on said first pin and havinga pair of side members resiliently biased inwardly towards one another;and a movable contact means mounted on said armature for slidingmovement between said side members of said U-shaped spring along thelongitudinal axis of said spring to contact said second pin when saidarmature is moved from one pivotal position to another,

said spring member maintaining continuous contact with said movablecontact for such movement of said armature.

2. The combination defined in claim 1 and in which said second pin isconfigured to have a bent-over end por tion in said envelope traversingthe path of said movable contact to be engaged by said movable contactupon the aforesaid movement of said armature.

3. The combination defined in claim 1 and which includes a thirdelectrically conductive pin extending through said envelope and into theinterior thereof, said third pin having a bent-over end portion Withinsaid envelope traversing the path of said movable contacts to benormally engaged thereby and to be disengaged thereby upon the aforesaidmovement of said armature.

4. The combination delined in claim 1 and which includes an insulatingpost mounted on said armature and extending outwardly from the planethereof, said movable contact being mounted as a conductive collar onthe end of said post remote from said armature.

5. The combination defined in claim 4 in which Said insulating post isstaked to said armature.

`6. The combination dened in claim 4 and which includes an electricallyconductive sleeve mounted on said post in coaxial relationship therewithand electrically connected to said collar, said sleeve engaging said U-shaped spring and completing an electric path between said collar andsaid lirst pin.

7. The combination defined in claim 6 in which said collar and saidsecond pin are formed of electrically conductive material of highrefractory characteristics.

8. The combination defined in claim 1 in which said envelope is composedof a ceramic material, and which includes vitreous seals interposedbetween said end wall and said envelope and between said pins and saidenvelope.

References Cited UNITED STATES PATENTS `8/1937 Thomas 174-5063 11/1962ReXer 174-506 11/1964 Loman 335-196 8/1967 De Lucia 335-260 9/1967Roessler 335--154 12/ 1967 Wildeboer 174-5061 U .S. C1. XR.

